The present invention relates to a multiplexing device for multiplexing two frequency bands B1, B2, in which the frequencies of B1 are lower than the frequencies of B2 and comprising, starting from the antenna input or lead-in for coupling to an antenna, a first polarization duplexer with a common guide for passing bands B1 and B2 and a second polarization duplexer for band B2.
The present invention more particularly relates to a two-band multiplexer constituted by the aforementioned multiplexing device. It also relates to a multiplexer for multiplexing more than two frequency bands and which has a multiplexing device according to the invention.
Multiplexers make it possible to group several frequency bands on a same antenna and have been used for a considerable time for covering the needs of terrestrial and spatial radio beams. These multiplexers are of the two-band, three-band and higher types. The polarizations of the waves are either plane or circular.
The common feature of these known multiplexers is that their mechanical complexity leads to a high cost price. Apart from the duplexer of the lowest band, which generally has a relatively simple construction, the duplexers for the other bands are complicated. Thus, they require, for example, two directional couplers with total coupling in series and respectively relating to the two polarizations of the wave to be transmitted in the considered band, or as from four coupling holes distributed at 90.degree. from one another about a common guide, they require a symmetrical structure formed from two pairs of guides, the guides of one pair arriving at two opposite holes and having to be joined together to form the input relative to one of the two polarizations. These known duplexers are also expensive, because they use expensive filters in the input guides of the different bands.